Thermalization of particle detectors: The Unruh effect and its reverse

Garay, Luis J.; Martín-Martínez, Eduardo; Ramón, José de

doi:10.1103/physrevd.94.104048

Cited by 58 publications

(73 citation statements)

References 22 publications

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“…This is answered with the response function of the Unruh-DeWitt detector. In the long time limit the response function (2.15) is proportional to the Fourier transform of the Wightman function (2.26) [14,15] and so a uniformly accelerated observer sees a thermal state. This is the manifestation of the Unruh effect understood in a precise way using the KMS condition.…”

Section: Accelerated Observers and The Unruh Effectmentioning

confidence: 99%

“…(3.21). Certainly the response functions divided by the time interval, F F (Ω, T )/T , approach thermal KMS states based on the long time limit [14,15] (see eq. (2.28) and Appendix D).…”

Section: Completing the Cyclementioning

confidence: 99%

“…In refs. [14,15] it is shown that in the long time limit the detector's response is the Fourier transform of the Wightman functionŴ φ , i.e. where χ 2 = (1/T ) R |χ(ω)| 2 dω = π 2 /2 for the Lorentzian switching function in eq.…”

Section: Long Time Limit Of the Response Functionsmentioning

confidence: 99%

“…The response function of this detector F(Ω, T ) represents the probability of detection over a time scale T . For a constantly accelerated observer at large times, this response function approaches a thermal state in the rigorous Kubo-Martin-Schwinger (KMS) sense [14,15], with Unruh temperature proportional to the acceleration, i.e T U ∝ α. In addition, these Unruh-DeWitt (UdW) detectors have been used to study unusual phenomena, such as harvesting entanglement from the quantum vacuum [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Scalar and fermionic Unruh Otto engines

Gray

Mann

2018

J. High Energ. Phys.

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We investigate the behaviour of quantum heat engines, in which a qubit is put through the quantum equivalent of the Otto cycle and the heat reservoirs are due to the Unruh effect. The qubit is described by an Unruh-DeWitt detector model coupled quadratically to a scalar field and alternately to a fermion field. In the cycle, the qubit undergoes two stages of differing constant acceleration corresponding to thermal contact with a hot and cold reservoir. Explicit conditions are derived on the accelerations required for this cycle to have positive work output. By analytically calculating the detector response functions, we show that the dimensionality of the quadratic and fermionic coupling constants introduces qualitatively different behaviour of the work output from this cycle as compared to the case in which the qubit linearly couples to a scalar field.

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Section: Accelerated Observers and The Unruh Effectmentioning

confidence: 99%

“…(3.21). Certainly the response functions divided by the time interval, F F (Ω, T )/T , approach thermal KMS states based on the long time limit [14,15] (see eq. (2.28) and Appendix D).…”

Section: Completing the Cyclementioning

confidence: 99%

Section: Long Time Limit Of the Response Functionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Scalar and fermionic Unruh Otto engines

Gray

Mann

2018

J. High Energ. Phys.

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“…This is the case of QFTs, where usually the partition function is illdefined. More formally, for a KMS stateρ β (with inverse KMS temperature β) with respect to time translations generated by a HamiltonianĤ the two-point correlator Wρ(τ, τ ) := Tr ρφ (t (τ ) x (τ ))φ (t (τ ) x (τ )) satisfies the following two conditions (see, among many others, [21,22]): 3 1. W ρ (τ, τ ) = W ρ (∆τ ) (Stationarity).2.…”

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confidence: 99%

Work Distributions on Quantum Fields

et al. 2019

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We study the work cost of processes in quantum fields without the need of projective measurements, which are always ill-defined in quantum field theory. Inspired by interferometry schemes, we propose a work distribution that generalizes the two-point measurement scheme employed in quantum thermodynamics to the case of quantum fields and avoids the use of projective measurements. The distribution is calculated for local unitary processes performed on KMS (thermal) states of scalar fields. Crooks theorem and the Jarzynski equality are shown to be satisfied for a family of spatio-temporally localized unitaries, and some features of the resulting distributions are studied as functions of temperature and the degree of localization of the unitary operation. We show how the work fluctuations become much larger than the average as the process becomes more localized in both time and space.Introduction.-At microscopic scales average quantities no longer characterize completely the state of a system or the features of a thermodynamic process. There, stochastic or quantum fluctuations become relevant, being of the same order of magnitude as the expectation values [1][2][3]. It is therefore important to develop tools that allow us to study the properties of these fluctuations to fully understand thermodynamics at the small scales.One of the best studied quantities in this context is work of out-of-equilibrium processes, and its associated fluctuations. The notion of work is an empirical cornerstone of macroscopic equilibrium thermodynamics. However, work in microscopic quantum scenarios is a notoriously subtle concept (e.g., it cannot be associated to an observable [4]), and although there is no single definition of work distributions and work fluctuations in quantum theory, several possibilities have been proposed (see e.g., [5]). Perhaps the most established notion of work fluctuations is that defined through the Two-Point Measurement (TPM) scheme [6,7], where the work distribution of a process is obtained by performing two projective measurements of the system's energy, at the beginning and at the end of the process. The TPM formalism defines a work distribution with a number of desirable properties: it is linear on the input states, it agrees with the unambiguous classical definition for states diagonal in the energy eigenbasis, and it yields a number of fluctuation theorems in different contexts [1,7,8].An important caveat of this definition is that it cannot be straightforwardly generalized to processes involving quantum fields: projective measurements in quantum field theory (QFT) are incompatible with its relativistic nature. They cannot be localized [9], they can introduce ill-defined operations due to UV divergences and, among other serious problems, they enable superluminal signaling even in the most innocent scenarios [10]. For these reasons, it has been strongly argued that projective measurements should be banished from the formalism of any relativistic field theory [10][11][12]. However, quantum fields are cert...

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Unruh-DeWitt Detectors Around (2+1)-Dimensional Black Holes

Smith

2019

Detectors, Reference Frames, and Time

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Thermalization of particle detectors: The Unruh effect and its reverse

Cited by 58 publications

References 22 publications

Scalar and fermionic Unruh Otto engines

Scalar and fermionic Unruh Otto engines

Work Distributions on Quantum Fields

Unruh-DeWitt Detectors Around (2+1)-Dimensional Black Holes

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